Charles, I just looked up the schematics for the Brewtus and realized a mistake in my reply and in my original post. I believe the difference is enough to damage my original hypothesis, but still leaves as a mystery the cause for the observed behavior.
The pressure of the brew boiler is isolated from the brew path by the 3-way switch in the E-61 grouphead, and not by the pump. (Doh!) Then this must mean that as soon as the 3-way switch is activated the pressure must momentarily drop a bit as the brew boiler is now instantly open to the brew path volume. The change in volume is minimal compared to the brew boiler volume, and so will cause a miniscule drop in pressure and therefore only a minuscule drop in water temperature. Quite a difference than what I had originally thought, which was a very gradual increase of pressure in the grouphead from atmospheric pressure to brewing pressure due mostly to the actions of the pump. Now I see that it will start out at boiler pressure, then gradually increase to brewing pressure. This still leaves something to be explained, which are the results of my experiment. I did mention an earlier hypothesis in another thread where I speculated whether or not the behavior is due to a s/w limit inside the controller on the maximum numeric temperature used to represent the brew boiler. Again I hope this is not the case, but could it be that the s/w inside the temp controller limits Ttarget_brew_temp - x to 100 deg C? This alternate hypothesis could still explain the observed behavior. On Feb 7, 8:49 pm, cgfan <[email protected]> wrote: > Charles, > > The boilers are pressurized, but the boiler pressure is isolated from > the brew path by the pump, which at the start of the shot is > essentially filling up an empty brew path with water. > > It is the initial filling of this brew path at the start of each shot > which causes the loss of pressure and the opportunity for the steam to > escape, resulting in brew water that's at most 100 deg C. At least > that's the hypothesis... > > On Feb 7, 8:38 pm, Charles Haynes <[email protected]> wrote: > > > Aren't the boilers pressurized? > > > -- Charles --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Brewtus" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/brewtus?hl=en -~----------~----~----~----~------~----~------~--~---
